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Yellowstone National Park is home to the largest population of free ranging genetically pure American bison (Bison bison). The current population estimate is 4,800 animals which utilize the parks grasslands throughout most of the year. In 2015, the National Park Service began an assessment of the effects of bison across the migratory range of both the Central and Northern Range herds that includes 23 field sites across the altitudinal migratory gradient. The effects of bison a population this size on grassland ecosystems has not been determined and in this study we present average consumption rates across the landscape and the contributions of plant available nutrients returned to soil by bison dung. To accomplish this each site has three fixed and five movable animal exclosures (moved every 4-6 weeks) that allow seasonal grazing consumption rates and plant available soil nutrients (nitrogen and phosphorous) to be quantified. Transects were used to quantify dung inputs and a subset of sampling was done seasonally for total mass and dung nutrient analysis. �Grazing consumption ranges from 10-70% across the migratory range and is correlated with the availability of soil moisture. Nitrogen inputs from dung ranged from 3-14 kg N/Ha and was closely correlated to consumption and altitude. Phosphorous inputs ranged from 0.8-3.5 kg P/Ha and were closely correlated with altitude and season. N and P content of dung varies seasonally with higher N and P in spring dung. These findings indicate that bison are removing a significant but spatially variable amount of grass biomass and returning a significant portion of the nutrients back to the system in the form of dung. This suggests that the fertilizer effect of bison dung contributes to the maintenance of productivity in Yellowstone grasslands.